Siege of Cagliari (1124)

The Siege of Cagliari occurred in 1124 when a Sicilian army under Captain Jacopo besieged the French-held Sardinian city of Cagliari. The Sicilian army was repulsed and destroyed in a French sortie, and the unprovoked Sicilian attack led to France retaliating with an invasion of Sicily.

Background
Starting in 1080, King Philip I of France and his son Louis VI of France consolidated the Kingdom of France's realm by subduing rebellious nobles in Burgundy, Flanders, and Aquitaine. Soon, their Council of Nobles asked them to capture Corsica, seeing it as a useful trade center. The French captured Ajaccio in 1102, with the future Louis VI of France and Admiral Thibault capturing the island city from its weak garrison. The French followed this up with the capture of Cagliari on Sardinia to the south, gaining a foothold in the Mediterranean.

However, France's involvement in Mediterranean politics came with a cost: it brought them into contact with the warring Italian states. One of the most powerful Italian states was the Norman-ruled Kingdom of Sicily, which controlled southern Italy and the island of Sicily. Sicily had been expanding across the Mediterranean, spreading its rule (and with it Catholicism) to Libya and Tunisia. Sicily had been eyeing Sardinia prior to the French conquest, and the Sicilian crown refused to allow for the French to acquire a foothold within the borders of present-day Italy, lest they attempt to conquer their fellow Francophone nation. In 1124, a small army of 294 troops under Captain Jacopo landed on Sardinia and laid siege to Cagliari, which was defended by 521 French troops under King Louis. This surprise attack began a war between France and Sicily, and Louis immediately set about lifting the siege.

Siege
Louis wasted no time about responding to the Sicilian invasion, launching a sortie before the Sicilians could even construct siege works. The French army arrayed itself in front of the city walls before marching towards the Sicilian army. The French army's archers fired on the Sicilians as the spearmen charged the Sicilian footsoldiers and the cavalry flanked around the Sicilian infantry to attack the Sicilian Muslim archers and mailed knights. In the ensuing battle, the French succeeded in enveloping the Sicilian army and destroying them; the Sicilians had withdrawn so that their back was near the water, but the French were still able to circle around and attack them from behind. The French utterly destroyed the Sicilian army, taking 132 prisoners. When the Sicilian king refused to ransom the captured Sicilian soldiers, Louis had no choice but to have all of them executed.

Aftermath
France's victory at Cagliari put an end to Sicily's attempts to conquer Sardinia, but Louis decided to retaliate in force. His army bolstered its ranks with additional mercenaries before setting sail across the Tyrrhenian Sea to the Sicilian coast. The French proceeded to besiege and storm Palermo, massacring its inhabitants; they later marched north and took Naples, conquering the Sicilian possessions in Italy and reducing them to their North African colonies, where they remained secure for over a century.